Hi, though the caption reads "premature ejaculation" you seem to be concerned about erections. Well, sure works but it is not an all in all solution. ED occurs for a variety of reasons and under different scenarios. Unless we understand the root cause, mere consumption of drugs will not help you in the long run. That's probably is what is happening to you.
Please consult a sex counselor/therapist in person. At least through video/phone appointment.
if your main problem is premature ejaculation then i suggest you stop using viagra as it is a medicine for not getting erection and not premature ejaculation.
You can try local anaesthetic sprays, stop and start technique and squeeze techniques to delay ejaculation. Please do an internet search for those words for explanation. If all else fails then you can try medicines like dapoxetine.